Pneumatic pressure control valve

Abstract

A pneumatic pressure control valve is described, comprising a housing (1) in which a valve chamber (2) is formed with a supply opening (3) for supplying compressed gas into the valve chamber (2), a connecting opening (4) for connection to a cushion to be filled with gas, and an actuator opening (5) for connecting the valve chamber (2) to an actuator chamber, wherein an actuator (20) with a movable adjusting element (7) is arranged in the housing (1), wherein the adjusting element (7) is formed with a plunger (11) projecting through the actuator opening (5), the end of which projecting into the valve chamber (2) is connected to a plate (6), wherein a membrane (8) is arranged in the valve chamber (2) and is connected airtight to the valve chamber wall and divides the valve chamber (2) into two regions,wherein the plate (6) of the tappet (11) is arranged in a first region (9) and is mechanically connected to the membrane (8) via a spring element (12), and wherein an actuating pin (13) of a valve plate (14) connected to the membrane (8) is arranged in a second region (10), wherein the valve plate (14) is arranged on the outside of the valve chamber (2) and, depending on the position of the membrane (8), opens or closes the supply opening (3) via the actuating pin (13), wherein the actuator (6) is an SMA actuator.

Description

[0001] The invention relates to a pneumatic pressure control valve, comprising a housing in which a valve chamber is formed with a supply opening for supplying compressed gas into the valve chamber, a connecting opening for connecting to a cushion to be filled with gas and an actuator opening for connecting the valve chamber to an actuator chamber, wherein an actuator with a movable adjusting element is arranged in the housing, wherein the adjusting element is formed with a plunger projecting through the actuator opening, the end of which projecting into the valve chamber is connected to a plate, wherein a membrane is arranged in the valve chamber, which is connected airtight to the valve chamber wall and divides the valve chamber into two areas,wherein the plate of the tappet is arranged in a first region and is mechanically connected to the diaphragm via a spring element, and wherein an actuating pin of a valve plate connected to the diaphragm is arranged in a second region, wherein the valve plate is arranged on the outside of the valve chamber and opens or closes the supply opening via the actuating pin depending on the position of the diaphragm.

[0002] Such a pressure regulator is shown and described on the website en.wikipedia.org / wiki / Pressure_regulator# / media / File:Single-stageregulator.svg and in the Fig. 1 shown.

[0003] DE 10 2018 205 016 A1 relates to a pressure reducer with a housing and with a valve which, when closed, separates an upstream pressure chamber from a downstream pressure chamber and, when open, connects the upstream pressure chamber and the downstream pressure chamber. The valve has a diaphragm acting on a valve tappet, on which a spring force of a spring element acting in the opening direction of the valve and a force acting in the closing direction of the valve, dependent on the pressure prevailing in the downstream pressure chamber, acts, providing a pressure reducer function. The valve has a valve body attached to the valve tappet. The spring element is arranged between two spring plates, wherein the spring element is firmly connected to a spring plate facing the diaphragm and to a spring plate facing away from the diaphragm, and wherein the spring plate facing the diaphragm is firmly connected to the valve tappet.The spring plate facing away from the diaphragm is operatively connected to an actuating element, via which the spring plate facing away from the diaphragm can be displaced relative to the spring plate facing the diaphragm in such a way that, depending on the relative position between the spring plates, the spring element acts as a compression spring, providing the pressure reducer function, or as a tension spring, providing a closing valve function.

[0004] DE 10 2021 203 190 A1 relates to a pneumatic valve, with a housing in which an air chamber is formed with a supply opening for supplying compressed air into the air chamber, a connecting opening for connecting the air chamber to an air cushion and a discharge opening for discharging compressed air from the air chamber, wherein an actuator with a movable closing element is arranged in the housing, wherein the closing element is provided with a first sealing element for closing the supply opening, with a second sealing element for closing the discharge opening and with a sealing element arranged between the first and the second sealing element and which, in the deactivated state, is pressed against the supply opening or the discharge opening.the drain opening is formed by an elastic element pressing on it, wherein a plunger projecting through the drain opening is arranged on the second sealing element, and wherein the actuator further comprises a printed circuit board, an actuating element which has an actuating section for acting on the plunger and a bending section connected to the actuating section and the printed circuit board, and an actuator element which has a first end which is mechanically connected to the actuating section and a second end which is mechanically and electrically connected to the printed circuit board, wherein the actuator element is designed to bend the bending section when energized such that the actuating section, by acting on the plunger, opens the drain opening by pressing the second sealing element against the elastic element.

[0005] US 2022 / 0 341 496 A1 relates to a seat support assembly for a valve, comprising an annular seat support body with an annular projection projecting radially into a central passage, and an annular plastic sealing ring molded onto the annular projection, the annular plastic sealing ring defining a seat seal.

[0006] The main function of such a pressure control valve is to adjust the gas flow through the regulator to the gas demand while maintaining a sufficiently constant output pressure. As the load flow decreases, the regulator flow must also decrease. As the load flow increases, the regulator flow must increase to prevent the regulated pressure from decreasing due to a lack of gas in the pressure system. It is desirable that the regulated pressure does not deviate significantly from the setpoint over a wide range of flow rates, but it is also desirable that the flow through the regulator be stable and that the regulated pressure is not subject to excessive oscillations.

[0007] A pressure regulator comprises a limiting element, a loading element and a measuring element: The restricting element is a valve that can provide variable flow restriction, such as a globe valve, butterfly valve, poppet valve, etc. The load element is a part that can exert the required force on the limiting element. This load can be provided by a weight, a spring, a piston actuator, or a diaphragm actuator in combination with a spring.

[0008] The measuring element serves to determine when the inlet flow equals the outlet flow. The diaphragm itself is often used as a measuring element; it can serve as a combined element.

[0009] In the Fig. In the single-stage regulator shown in Figure 1, a force balance on the diaphragm 8 is used to actuate a poppet valve 13, 14 to regulate the pressure. With no inlet pressure, the spring 12 above the diaphragm 8 pushes it onto the poppet valve 13, 14 and holds it open. Once the inlet pressure is introduced, the open poppet 14 allows flow to the diaphragm 8 and the pressure in the upper chamber 9 rises until the diaphragm 8 is forced upwards against the spring 12, causing the poppet 14 to reduce flow and eventually stop any further pressure rise. By adjusting the upper screw 7, the downward pressure on the diaphragm 8 can be increased, requiring more pressure in the upper chamber 9 to maintain balance. In this way, the output pressure of the regulator is regulated.

[0010] The loading element is acted upon by an adjusting screw 7, by means of which the preload of the loading element, e.g. a spring 12, between a plate 6 arranged at the end of the adjusting screw 7 and the membrane 8 can be adjusted almost continuously.

[0011] In vehicles, fillable, elastic cushions are used to shape seat contours. These cushions are typically filled with air. Electrically operated valves are used to control the air flow. Shape memory wire (SMA = shape memory alloy) is increasingly being used as an actuator for such valves. This wire shortens in length when a current flows and the resulting heat builds up.

[0012] Due to the thermal actuation principle, switching processes in SMA valves are slower than in corresponding solenoid or piezo valves. This applies particularly to the actuator's shutdown process, which can also vary depending on ambient conditions (temperature, flow, etc.). This makes it difficult to precisely shut off when a target pressure is reached, and the achieved pressure becomes increasingly inaccurate the shorter the filling or venting process.

[0013] Rapidly reaching the target pressure is particularly necessary for highly dynamic functions, such as fast massage sequences, as well as for functions that require cushion adjustment depending on driving dynamics.

[0014] The following state-of-the-art options are available for quickly and accurately setting different target pressures: When using an SMA actuator with a high surface-to-volume ratio (e.g., very thin wire or strip), cooling occurs quickly. However, with small actuator cross-sections, its service life is reduced, as defects lead more quickly to fracture and thus to actuator failure.

[0015] DE 10 2023 202 254 B3 describes a valve arrangement in which the precise switching on and off of the air flow is carried out with a fast-switching magnetic or piezoelectric pilot valve and only the distribution of the air to different cushions is carried out with SMA valves.

[0016] DE 10 2005 060 217 B4 describes an SMA valve with targeted shielding of the wire from air flow. If this principle is further developed, it can also be reversed, for example, to quickly cool the wire with targeted air flow.

[0017] A pneumatic pressure control valve as described above can be adjusted to the desired target pressure using the adjusting screw, ensuring that this target pressure is reliably achieved even with a slow-acting SMA valve. However, to accommodate a wide range of customer functions, different target pressures are required for different functions.

[0018] Multiple pressure regulators can be set to different pressures and optionally connected to outlet-side consumers using pilot valves. However, the pilot valves must be designed for the maximum flow rate.

[0019] DE 10 2019 208 051 B4 describes a valve with an SMA actuator, wherein the pivot point of a bender and the SMA wire are arranged on different sides of a circuit board.

[0020] The object of the invention is to provide a pneumatic pressure control valve for setting at least two different target pressures, which can be switched by means of a simple electrically controllable actuator. This object is achieved in a generic pressure control valve in that the actuator is an SMA actuator and preferably further comprises: a circuit board arranged in the actuator chamber, an actuating element arranged in the actuator chamber, which has an actuating section for acting on the plunger and a bending section connected to the actuating section and the circuit board, and an actuator element arranged in the actuator chamber, which has a first end that is mechanically connected to the actuating section and a second end that is mechanically and electrically connected to the circuit board, wherein the actuator element is designed toin a de-energised state, to bring the actuating element into a first state in which it presses the spring element against the diaphragm via the plunger, and in a energised state, to bring the actuating element into a second state in which the actuating section exerts less force on the plunger, so that the spring acts less strongly on the diaphragm.

[0021] The SMA actuator simply changes the force of the spring in the pressure regulator so that its output pressure can be regulated to at least two different values ​​by electrical control.

[0022] In an advantageous design of the pneumatic pressure control valve, the diaphragm is clamped hermetically between two valve chamber wall sections. This allows for a very simple construction.

[0023] The membrane can have a thickening in its center on which the spring element can be supported, which enables a one-piece, simple design.

[0024] In a further advantageous embodiment of the pneumatic pressure control valve, the actuator has a position sensor to detect the movement path of the actuating element and thus the compression of the spring element.

[0025] This makes it possible, in an advantageous further development, to provide a control device which is operatively connected to the position sensor and which controls the actuator element depending on a predetermined position value in order to set a predetermined spring element compression.

[0026] The invention will be described in more detail below using exemplary embodiments with the aid of figures. Fig. 1 a pressure control valve according to the state of the art, Fig. 2 the valve chamber of a pressure control valve with a tappet actuated by an SMA actuator in an open state in a first spring element preload state, Fig. 3 the valve chamber of the pressure control valve of the Fig. 2 with a plunger actuated by an SMA actuator in a closed state in the first spring element preload state, Fig. 4 the valve chamber of the pressure control valve of the Fig. 2 with a plunger actuated by an SMA actuator in an open state in a second spring element preload state, Fig. 5 the valve chamber of the pressure control valve of the Fig. 2 with a plunger actuated by an SMA actuator in a closed state in the second spring element preload state, Fig. 6 a pressure control valve according to the invention with an SMA actuator in a first state and Fig. 7 the pressure control valve according to the invention with an SMA actuator in a second state.

[0027] The Fig. 2 to 5 show a valve chamber 2 of a pneumatic valve, such as is used in a pressure control valve according to Fig. 6 and Fig. 7, each in a cross-sectional view, which essentially corresponds to the structure of the known valve chamber, as already described in Fig. 1 and described above. Identical parts are provided with the same reference numerals and are not labeled in all figures for the sake of clarity. Unlike the pressure control valve of the prior art, the spring 12 is pressed by a plate 6 against the diaphragm 8, which is connected to a plunger 11, the position of which can be changed by an SMA actuating element 22. Fig. Figures 2 to 5 show two positions, each defined by mechanical stops either of the actuating section 23 on the outside of the cover of the valve chamber 2 or of the plate 6 on its inside. However, it is also readily possible to set intermediate positions.

[0028] A pressure control valve with such a design can therefore be easily adjusted electrically.

[0029] The SMA actuator changes the force of the spring in the pressure regulator so that its output pressure can be regulated to different values.

[0030] The following describes the function of the pressure control valve of the Fig. 2 to 5. The pressure control valve has an elastic diaphragm 8, which hermetically divides the valve chamber 2 into a lower 10 and an upper 9 valve chamber. In the depressurized state, a spring 12 presses the diaphragm 8 downward, thus opening the sealing seat of the valve 14, which can be designed as a poppet valve. This allows the pre-pressure P1 to flow into the lower valve chamber 10; this, in turn, can be connected to outlet-side consumers (e.g., additional SMA valves, not shown).

[0031] In the steady state, the spring force opens the valve plate 14 and the pressure force of the lower valve chamber 10 of the pressure regulator closes it, so that a target pressure P2 is established at the output. The level of the target pressure P2 depends on the force of the spring 12. The length of the spring 12 can be adjusted to at least two different positions using an SMA actuator. This is achieved by the plunger 11 actuated by the SMA actuator with an attached plate 6, which receives the upper end of the spring 12. The upper valve chamber 9 of the pressure control valve is also connected to the ambient pressure via the actuator opening 5 for the plunger 11. The end positions of the plate 6 are preferably mechanically defined, e.g.by the plate 6 resting on the inside of the upper valve chamber 9 of the pressure control valve and / or by the actuating section 23 of the SMA actuator 22 resting on the outside of the upper valve chamber 9 of the pressure control valve, whereby the upper end of the plunger 11 is held flush with the outside of the valve chamber 2.

[0032] Fig. Figure 2 shows the pressure control valve with the SMA actuator not actuated, with the plunger 11 and plate 6 assuming a lower end position, in which the spring 12 of the pressure control valve has a substantially short length. Fig. 2, the valve 14 of the pressure control valve is shown in the open position, for example, when the target pressure P2 has not yet been fully reached. Fig. 3, the valve 14 is shown in the closed position when the first target pressure P2 is reached.

[0033] Fig. Figure 4 shows the valve chamber 2 of the pressure control valve with the SMA actuator actuated, with the plunger 11 and plate 6 assuming an upper end position, in which the spring 12 of the pressure control valve has a substantially large length. Fig. 4, the valve 14 of the pressure control valve is shown in the open position, for example, when the second target pressure P3 has not yet been fully reached. Fig. 5, the valve 14 is shown in the closed position when the second target pressure P3 is reached.

[0034] Due to the greater length of the spring 12 in the Fig. 3 and Fig. 4 the spring force is lower there than in the Fig. 2 and Fig. 3 and thus the second target pressure P3 is smaller than the first target pressure P2.

[0035] Fig. 4 shows the pressure control valve with the SMA actuator not actuated, wherein the actuating section 23 of the SMA actuator rests on the outside of the upper valve chamber 9 of the pressure control valve and thus the plunger 11 and plate 6 assume a defined lower mechanical position.

[0036] Fig. Figure 5 shows the pressure control valve with the SMA actuator actuated, with the actuating section 23 of the SMA actuator releasing the plunger 11. The plate 6 of the plunger 11 therefore rests against the inside of the upper valve chamber 9 of the pressure control valve and thus assumes a defined upper mechanical position.

[0037] In the Fig. 6 and Fig.Figure 7 shows a pressure control valve in a non-actuated and an actuated state. The pressure control valve is formed with a housing 1 having a first housing part 17, which in the illustrated embodiment is designed as a base plate. The housing 1 also has a second housing part 18, which is designed as a cover, and finally a third cup-shaped housing part 19, which is designed as an insert between the first and second housing parts 17, 18 and onto which a supply connection 27 and a connecting connection 28 are formed. The valve chamber 2, which is operatively connected to an actuator 20, is formed between the third housing part 19 and the second housing part 18.

[0038] The valve chamber 2 is formed on the third housing part 19 by having a cup-shaped portion into which a cover of the valve chamber 2 is inserted. The connection between the cup-shaped portion and the cover is established, for example, by means of a press fit or a projection on the cover that engages a groove in the cup-shaped portion. It can be advantageous if the pressure and sealing forces are absorbed by such clipping, screwing, etc.

[0039] The valve chamber 2 has a supply opening 3, a connection opening 4, and an actuator opening 5. In the illustrated embodiment, the supply opening 3 and the connection opening 4 are formed in the third housing part 19, and the actuator opening 5 is formed in the cover closing the valve chamber 2. Compressed air can therefore be fed into the housing 1 via the supply connection 27, for example from a compressor, whereby the compressed air can reach the valve chamber 2 via the supply opening 3 and from there via the connection opening 4 and the connection connection 28 into a connectable air cushion or another load, such as a downstream valve.

[0040] An actuator 20 is also arranged in the housing 1. The actuator 20 is formed with a circuit board 21, which is mounted and mechanically connected to corresponding struts of the third housing part 19. Connected to the circuit board 21 is an actuating element 22, which has an actuating section 23 that is in direct contact with the plunger 11 and has a bending section 24 that is connected to the circuit board 21.

[0041] The actuator 20 further comprises an actuator element 26, which is preferably formed with a wire made of a shape memory alloy that shortens when subjected to current supplied by a circuit (not shown) on the circuit board 21. In the non-activated state, the actuating element 22 is preloaded such that the actuating element 22 presses with its actuating section 23 against the plunger 11, thereby preloading the spring element 12.

[0042] The actuator element 26 is connected - for example by means of crimp connections - both to the actuating element 23 and to the circuit board 21.

[0043] Advantageously, an end position detection element 25 is formed on the actuating element 22, which comes into contact with the circuit board 21 when the actuator 20 is actuated and enables a current flow, whereby it is detected that the end position has been reached, so that the current through the actuator element 26 can be switched off or at least reduced in order not to overload it.

[0044] This end position detection element 25 could also be developed into a position sensor in order to detect the height at which the actuating section 23 is located and thus the position of the plunger 11 in order to be able to set different preloads of the spring element 12.

[0045] The pressure control valve according to the invention can advantageously be followed by additional valves, such as SMA valves, which selectively transmit the pressure to different consumers. Such consumers can be, for example, air chambers for contour adjustment or for a massage function in vehicle seats.

[0046] The advantages of the above-mentioned designs compared to currently available state-of-the-art solutions are summarized below: Thanks to the switchable pressure control valve, slow-acting SMA valves can also be used at high supply pressures (i.e., greater than the target pressure). Different pressure levels enable different intensities in the stroke or speed of a contour adjustment or massage sequence.

[0047] The SMA actuator does not require rapid switching operations. It can also remain continuously actuated for extended periods (e.g., during a massage sequence with constant target pressures). Both of these factors favor the use of an SMA actuator for changing the length of the pressure regulator spring.

Claims

[1] Pneumatic pressure control valve, comprising a housing (1) in which a valve chamber (2) is formed with a supply opening (3) for supplying compressed gas into the valve chamber (2), a connecting opening (4) for connection to a cushion to be filled with gas and an actuator opening (5) for connecting the valve chamber (2) to an actuator chamber, wherein an actuator (20) with a movable adjusting element (7) is arranged in the housing (1), wherein the adjusting element (7) is formed with a plunger (11) projecting through the actuator opening (5), the end of which projecting into the valve chamber (2) is connected to a plate (6), wherein a membrane (8) is arranged in the valve chamber (2) which is connected airtight to the valve chamber wall and divides the valve chamber (2) into two regions, wherein the plate (6) of the tappet (11) is arranged in a first region (9) and is mechanically connected to the membrane (8) via a spring element (12), and wherein an actuating pin (13) of a valve plate (14) which is connected to the membrane (8) is arranged in a second region (10), wherein the valve plate (14) is arranged on the outside of the valve chamber (2) and, depending on the position of the membrane (8), opens or closes the supply opening (3) via the actuating pin (13), characterized by , that the actuator (6) is an SMA actuator. [2] Pneumatic pressure control valve according to claim 1, characterized by that the actuator (20) further comprises: - a circuit board (21) arranged in the actuator chamber, - an actuating element (22) arranged in the actuator chamber, which has an actuating section (23) for acting on the plunger (11) and a bending section (24) connected to the actuating section (23) and the circuit board (21), and - an actuator element (26) arranged in the actuator chamber, which has a first end which is mechanically connected to the actuating section (23) and a second end which is mechanically and electrically connected to the circuit board (21), wherein the actuator element (26) is designed, in a non-energized state, to bring the actuating element (23) into a first state in which it presses the spring element (12) against the membrane (8) via the plunger (11), and, in a energized state, to bring the actuating element (23) into a second state in which the actuating section (23) exerts less force on the plunger (11), so that the spring (12) acts less strongly on the membrane (8). [3] Pneumatic pressure control valve according to claim 1 or 2, characterized by that the membrane (8) is clamped airtight between two valve chamber wall parts. [4] Pneumatic pressure control valve according to one of claims 1 to 3, characterized by that the membrane (8) has a thickening in its center on which the spring element (12) is supported. [5] Pneumatic pressure control valve according to one of claims 1 to 4, characterized by that the actuator (20) has a position sensor to detect the movement path of the actuating element (23) and thus the compression of the spring element (12). [6] Pneumatic pressure control valve according to claim 5, characterized by that a control device is provided which is operatively connected to the position sensor and which controls the actuator element (26) depending on a predetermined position value in order to set a predetermined spring element compression.

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